Drill bit with variable drilling diameter and using method thereof

Abstract

The invention discloses a drill bit with the variable drilling diameter and a using method thereof.The drill bit comprises a drill bit body, a blade and a driving mechanism, and the drill bit body is columnar; a slurry channel is formed in the drill bit body. The blade is rotationally connected to the drill bit body. The driving mechanism is connected with the blade and used for driving the blade to rotationally unfold or retract to change the diameter of the drill bit; the diameter of the drill bit can be adjusted, the drilling efficiency is improved, the construction cost is reduced, and the adaptability of the drill bit under different stratum conditions is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering equipment, and in particular relates to a drill bit with a variable drilling diameter and a use method thereof. Background Art

[0002] With the rapid development of modern engineering construction, the requirements for drilling technology in fields such as infrastructure construction, energy extraction and geological exploration are increasing.

[0003] Traditional fixed-diameter drill bits have the following problems under complex and changeable geological conditions: 1. Low efficiency: drilling holes of different diameters requires frequent replacement of drill bits, resulting in reduced construction efficiency and extended construction period. 2. Increased costs: Frequent replacement of drill bits increases equipment investment and labor costs, and construction costs rise. 3. Poor adaptability: fixed-diameter drill bits are difficult to adapt to changes in formation hardness and hole diameter, affecting drilling quality.

[0004] Although some expandable drill bits are designed in the prior art, they generally have problems such as complex structure, poor reliability, and limited applicable formations, and cannot meet the needs of modern engineering for efficient, reliable, and multifunctional drill bits. Summary of the invention

[0005] The purpose of the present invention is to provide a variable drilling diameter drill bit and a method of using the same, so as to solve the problems of low efficiency, high cost, poor adaptability, etc. in the prior art, so as to realize the adjustability of the drill bit diameter, improve drilling efficiency, reduce construction costs, and enhance the adaptability of the drill bit under different formation conditions.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a variable drilling diameter drill bit, including a drill bit body, a blade and a driving mechanism, wherein the drill bit body is configured to be columnar; a mud channel is arranged inside the drill bit body; the blade is rotatably connected to the drill bit body; the driving mechanism is connected to the blade and is used to drive the blade to rotate, expand or retract to change the drill bit diameter.

[0008] Preferably, the driving mechanism is configured as a piston-connecting rod mechanism; the piston-connecting rod mechanism includes a hydraulic system, a hydraulic channel, a hydraulic piston and a connecting rod, the hydraulic channel is arranged in the drill bit body, the hydraulic piston is arranged in the hydraulic channel, and is connected to the blade through a connecting rod; the hydraulic channel is connected to the hydraulic system through a hydraulic pipeline, and is used to pass hydraulic oil; the hydraulic piston is used to drive the connecting rod to move under the action of the hydraulic oil, and drive the blade to rotate through the connecting rod.

[0009] Preferably, the driving mechanism is configured as a screw-slider mechanism; the screw-slider mechanism includes a screw, a screw channel and a slider, the screw channel is arranged in the drill bit body, the screw and the slider are arranged in the screw channel; the slider has an internal threaded hole and is threadedly connected to the screw; the slider is connected to the blade.

[0010] Preferably, the driving mechanism is configured as a cam mechanism; the cam mechanism comprises a cam channel and a cam, the cam channel is disposed in the drill body, the cam is disposed in the cam channel, and the cam is in contact with the blade.

[0011] Preferably, the number of the blades is at least two, and the plurality of blades are evenly distributed along the circumferential direction.

[0012] Preferably, the blade is rotatably connected to the drill body via a hinge.

[0013] Preferably, the hinge comprises a hinge shaft and a hinge seat, the blade and the drill body are respectively provided with the hinge seats, and both ends of the hinge shaft are respectively connected to the hinge seats.

[0014] Preferably, the drill bit body is provided with a limiter for limiting the rotational expansion angle of the blade.

[0015] Preferably, a joint for connecting to a drilling rig is provided on the top of the drill body.

[0016] In a second aspect, the present invention provides a method for using the variable drilling diameter drill bit according to the first aspect, comprising the following steps:

[0017] Installing the blade: Connecting the top end of the drill body to the drilling machine;

[0018] Retracting the blade: turning on and operating the drive system to drive the blade to rotate and retract, so that the diameter of the drill bit is reduced;

[0019] Start drilling: provide torque and drilling pressure through the drilling rig to drive the drill bit body downward, so that the bottom end of the drill bit body cuts the formation, and mud flows out of the mud channel and takes out rock cuttings;

[0020] Increase the drilling diameter: start and reverse the driving system to drive the blade to rotate and expand, so that the diameter of the drill bit increases.

[0021] The variable drilling diameter drill bit and the use method thereof provided by the present invention have the following beneficial effects:

[0022] The variable drilling diameter drill bit and the use method thereof provided by the present invention can solve the problems of low efficiency, high cost, poor adaptability and the like existing in the prior art, so as to realize the adjustability of the drill bit diameter, improve drilling efficiency, reduce construction cost, and enhance the adaptability of the drill bit under different formation conditions; it is suitable for the fields of oil and gas exploitation, geothermal resource development, tunnel excavation and pile foundation construction, and can realize drilling of different diameters in the same borehole; it can change its own diameter during the drilling process, meet the requirements of different projects for the borehole size, and complete the hole expansion operation without changing the drill bit.

[0023] The variable drilling diameter drill bit and the use method thereof provided by the present invention have the following advantages:

[0024] 1. Efficient drilling: Through the controllable expansion and retraction of the blade, the drill bit diameter can be flexibly adjusted, the drilling efficiency is improved, which is conducive to continuous operation and shortening the construction period; saving equipment, labor and time costs, which is conducive to reducing costs and improving economic benefits.

[0025] 2. Improve reliability: The blade and drill body can be made of high-strength, wear-resistant materials, and can undergo strict heat treatment and surface treatment to ensure reliability under high-load conditions, extend the service life of the drill bit, reduce maintenance and replacement frequency, and reduce disturbance and impact on the environment; increase drilling speed and reduce energy consumption.

[0026] 3. Easy operation: The blade can be driven to rotate through the hydraulic system, which can make the blade control more precise. The operator can monitor and adjust in real time on the ground, improve the safety and convenience of construction, and ensure that the blade can be smoothly deployed and retracted in different strata; it is convenient to clean, disassemble, replace, install and maintain on site, reducing downtime caused by equipment failure or maintenance.

[0027] 4. Wide adaptability: By replacing the material of the blade cutting edge and optimizing the drilling parameters, the drill bit can adapt to a variety of different geological conditions such as hard geology, soft geology and soft geology, enhance the adaptability of the drill bit in different formations, expand the scope of application; ensure the reliability of the drill bit under high load and complex environment.

[0028] 5. Improve work reliability: Connecting rods, hinges and other active mechanisms can be used to prevent jamming and failure, ensuring the reliability of the drill bit's diameter-changing operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of a variable drilling diameter drill bit provided by an embodiment of the present invention.

[0030] Figure 2 It is a flow chart of a method for using a variable drilling diameter drill bit provided by one embodiment of the present invention.

[0031] Reference numerals in the figures:

[0032] 1. Drill bit body, 101. Mud channel, 102. Hydraulic channel, 103. Joint, 2. Blade, 201 is the blade body, 202 is the cutting edge, 3. Hydraulic piston, 4. Connecting rod, 5. Control valve, 6. Hinge shaft. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below through the accompanying drawings and specific embodiments.

[0034] Embodiment 1

[0035] Please refer to Figure 1 The present embodiment provides a variable drilling diameter drill bit, including a drill bit body 1, a blade 2 and a driving mechanism. The drill bit body 1 is configured in a columnar shape; a mud channel 101 is configured inside the drill bit body 1; the blade 2 is rotatably connected to the drill bit body 1; the driving mechanism is connected to the blade 2, and is used to drive the blade 2 to rotate, expand or retract, so as to change the drill bit diameter.

[0036] Among them, the drill bit body 1 can be set to a cylindrical shape. The initial diameter of the drill bit body 1 when the blade 2 is fully retracted can be set to 1.5m. The drill bit body 1 can be made of high-strength alloy steel. The bottom end of the drill bit body 1 is the working end. Reinforcing ribs can be set inside and outside the drill bit body 1 to increase the rigidity and strength of the structure and resist the torque and axial pressure during drilling. The length of the drill bit body 1 can be 2m, which meets the requirements of accommodating the driving mechanism and providing sufficient structural strength. The wall thickness of the drill bit body 1 can be 50-100mm to ensure that no deformation or cracking occurs under maximum load.

[0037] The mud channel 101 may be opened at the central axis position of the drill bit body 1. The diameter of the mud channel 101 may be set to 100-200 mm to ensure sufficient mud flow.

[0038] The rotation axis of the blade 2 can be perpendicular to the rotation axis of the drill bit body 1. The blade 2 includes a blade body 201 and a cutting edge 202. The blade body 201 can be set to a wing-shaped or arc-shaped design, and the cutting edge 202 is set at its leading edge to meet the cutting requirements of different formations. For example, the blade 2 can be set to a rhombus shape, and the top angle position of one end of the blade 2 is rotatably connected to the drill bit body 1.

[0039] The base of the blade body 201 can be made of 42CrMo alloy steel. The cutting edge 202 can be inlaid with YG type hard alloy or polycrystalline diamond (PDC) to improve cutting performance and wear resistance.

[0040] The front angle of the cutting angle of the blade 2 can be 10-20°, and a smaller front angle is used in hard formations. The back angle of the cutting angle of the blade 2 can be 5-10° to ensure that the blade 2 does not rub excessively against the hole wall after cutting.

[0041] The front angle refers to the top angle of the front end of the blade 2, which is used for cutting the formation; the back angle refers to the top angle of the rear end of the blade 2, and the blade 2 is rotatably connected to the drill body 1 at the back angle position.

[0042] Nozzles can be installed at the bottom of the drill bit body 1 and at the position of the blade 2 of the drill bit body 1 to spray high-pressure mud, cool the blade 2, and remove rock chips generated by cutting.

[0043] Specifically, at least two blades 2 are provided, and the plurality of blades 2 are evenly distributed along the circumference, that is, the plurality of blades 2 are evenly distributed around the blade body 1, which is conducive to ensuring the rotation balance. For example, the blades 3 are provided in three or four forms.

[0044] Specifically, the blade 2 is rotatably connected to the drill body 1 through a hinge, and can be smoothly unfolded from a retracted state to a maximum diameter during the drilling process of the drill, so that the unfolded diameter of the blade 2 can be adjusted as needed. For example, the maximum diameter that the blade 2 can be rotatably unfolded is set to 2.5m, and the maximum diameter of the drill is 2.5m.

[0045] The inner side of the blade 2 is connected to the driving mechanism, and the outer side of the blade 2 is provided with a limiter, through which the maximum unfolding angle of the blade 2 is controlled.

[0046] Specifically, the hinge can adopt existing technology products, which can include a hinge shaft 6 and a hinge seat. The blade 2 and the drill body 1 are respectively provided with hinge seats, and the two ends of the hinge shaft 6 are respectively connected to the hinge seats, so that the blade 2 can rotate within a set angle range.

[0047] The hinge shaft 6 can be made of 40CrNiMo alloy steel, which can be heat treated and surface nitrided to have high strength and wear resistance. The diameter of the hinge shaft 6 can be 80-120 mm. The hinge shaft 6 can also be provided with a seal to prevent mud and impurities from entering and ensure smooth movement of the hinge shaft 6; the seal here can also be made of fluororubber or polytetrafluoroethylene (PTFE) seals, such as sealing rings or sealing lips or a combination of the two. Similarly, multiple seals can be provided to improve the sealing effect.

[0048] The length of the blade 2 from the hinge axis 6 to the outer edge can be determined according to the maximum expansion diameter of the drill bit, and needs to meet the maximum value of the drill bit diameter after expansion, for example, the maximum drill bit diameter requirement of 2.5m. The thickness of the blade 2 can be 30-50mm, meeting the weight and strength requirements.

[0049] Specifically, the drill body 1 is provided with a limiter to limit the rotational expansion angle of the blade 2, so as to control the maximum expansion angle of the blade 2 and prevent the blade 2 from over-rotating. For example, the limiter can be set as a pin, and the pin can be parallel to the rotation axis of the blade 2.

[0050] Specifically, a joint 103 for connecting to a drilling rig is provided at the top of the drill bit body 1, which is conducive to ensuring power transmission and reliable connection. For example, the joint 103 can be used to connect a drill rod of a drilling rig. The joint 103 can be set as a threaded interface or a flange interface, so that the end of the drill rod can be screwed into a threaded interface of an internal threaded hole, or the end of the drill rod can be connected to the flange interface.

[0051] In addition, a lubrication channel may be provided inside the drill body 1, and lubricating oil may be introduced into the lubrication channel to deliver lubricating oil or grease to various lubrication points to lubricate moving parts such as hinges and reduce friction and wear. The lubrication channel may be connected to a lubrication pump to regularly supply oil to the lubrication points. A lubrication nozzle may also be provided outside the drill body 1, and maintenance personnel may regularly add lubricant through a grease gun to achieve manual lubrication.

[0052] A spring may be connected between the blade 2 and the drill body 1. That is, the top of the blade 2 may be rotatably connected to the drill body 1, and the bottom of the blade 2 may be connected to the drill body 1 via a spring.

[0053] Dust covers or protective sleeves may be provided at locations susceptible to contamination, such as hinges and connecting rods 4 .

[0054] Locking device: Designed mechanical locking mechanism to ensure that the blade is stable in the retracted state and will not be accidentally deployed due to vibration or reaction force.

[0055] The locking device includes:

[0056] The locking pin is a cylindrical pin inserted into a preset locking hole or groove. When the blade 2 is in the retracted state, the locking pin extends and engages with the locking groove of the drill body 1, thereby preventing the blade 2 from being accidentally deployed;

[0057] The locking sleeve is a structural component fixed between the blade 2 and the drill body 1, and is used to guide and fix the locking pin to ensure that the locking pin can accurately enter the locking hole or groove;

[0058] A spring mechanism is provided with a spring, which automatically pushes the locking pin into the locking position; when the external force is released, the spring keeps the locking pin in the inserted state;

[0059] The release mechanism may be a mechanical lever, a handle or a solenoid valve control mechanism. When the blade 2 needs to be unfolded, the release mechanism pulls back the locking pin so that the blade 2 can move freely.

[0060] The locking pin is installed in the locking sleeve and connected to the fixed part of the blade 2. The locking sleeve is fixed at the connection between the drill body 1 and the blade 2. The spring mechanism is fixedly connected to the locking pin, one end of the spring is pressed on the locking pin, and the other end is fixed to the inner wall of the locking sleeve. The release mechanism is connected to the locking pin, and when needed, the locking pin is pulled to make the locking pin disengage from the locking groove.

[0061] All components of the locking device are mounted at the interface between the drill body 1 and the blade 2 through mechanical cooperation, forming a complete locking system together.

[0062] The locking device works as follows:

[0063] In the normal state of the blade 2, when the blade 2 is in the retracted state, the spring pushes the locking pin so that the locking pin is inserted into the locking groove of the fixed part of the drill body 1 or the blade 2. At this time, a mechanical buckle is formed between the locking pin and the locking groove to prevent the blade 2 from being accidentally unfolded due to vibration or reaction force.

[0064] When the blade 2 needs to be unfolded, the operator activates the release mechanism. Under the action of the release mechanism, the locking pin is pulled out of the locking slot, and the spring is compressed in a controlled manner. At this time, the blade 2 can rotate around the hinge to perform the unfolding operation. When the blade 2 is unfolded to the right position, if the unfolded state of the blade 2 needs to be locked, the locking pin can be automatically or manually reset and inserted into the locking slot to fix the blade 2 in the unfolded position.

[0065] In the event of a hydraulic system failure, the release mechanism can be manually operated to immediately pull back the locking pin to ensure that the blade 2 is in a retracted state, so that the drill bit can be safely withdrawn from the drilling hole.

[0066] Angle and displacement sensors are installed at the blade 2 or the connecting rod 4 to monitor the deployment angle and position of the blade 2 in real time.

[0067] The drill bit may also be provided with an alarm system to promptly remind the operator to take measures when the blade 2 cannot be normally deployed or retracted.

[0068] The alarm system includes a sensor module, a control unit, an alarm output device and a power module. Each part is connected to the main control system of the drill through a protection line.

[0069] The sensor module is installed on the blade 2 deployment / retraction mechanism, such as at a hinge or near a hydraulic piston. The sensor can use a position sensor, such as a magnetic sensor, a photoelectric encoder, or a linear differential transmitter, which can detect the position change of the blade 2 in real time. The sensor transmits the collected data to the main control unit via a shielded cable or a protected wireless module.

[0070] The main control unit includes core components, software, interfaces, alarm output devices and power modules. The core components of the main control unit are microcontrollers or PLCs, which are used to collect and process sensor data. The software logic of the main control unit: built-in preset thresholds and judgment algorithms are used to determine whether the blade 2 is normally deployed or retracted. The interface of the main control unit: connected to the sensor module, alarm output device and drilling control system through digital and analog interfaces. The alarm output device of the main control unit may include an LED indicator and a buzzer, which can send visual and auditory signals at the same time to achieve display and sound alarms. The alarm signal of the main control unit can also be transmitted to the ground control console or operation panel, which is convenient for the operator to check in time to achieve remote prompts. The power module of the main control unit provides a stable DC power supply for the entire alarm system, ensuring normal operation in harsh environments and achieving stable power supply.

[0071] The working principle of the main control unit is as follows:

[0072] The sensor module continuously detects the actual position of the blade 2 and sends the data to the main control unit in real time; the main control unit determines the movement state of the blade 2 according to the preset normal position range to achieve real-time monitoring.

[0073] If it is detected that the blade 2 fails to reach the target position of expansion or retraction within the specified time, or the motion data exceeds the allowable range, the main control unit will consider that there is a fault; at the same time, the main control unit can also monitor other relevant parameters, such as the hydraulic system status, to assist in determining the cause of the fault, so as to achieve fault determination;

[0074] When the system determines an abnormal situation, the main control unit immediately activates the alarm output device; the LED light flashes and the buzzer sounds, and the alarm signal is transmitted to the ground control console to remind the operator to trigger the alarm;

[0075] The data and fault information of the entire alarm process will be recorded in the system log for subsequent analysis and maintenance, so as to achieve feedback and records;

[0076] After receiving the alarm, the operator can retract the blade 2 through the manual operation mechanism to ensure that the drill bit is safely out of the hole; the alarm system can effectively monitor the status of the blade 2 and can provide timely reminders in case of abnormalities to ensure the safety and stability of the drill bit during drilling.

[0077] In one embodiment, the driving mechanism is configured as a piston-connecting rod mechanism; the piston-connecting rod mechanism includes a hydraulic system, a hydraulic channel 102, a hydraulic piston 3 and a connecting rod 4, the hydraulic channel 102 is arranged in the drill body 1, the hydraulic piston 3 is arranged in the hydraulic channel 102, and is connected to the blade 2 through the connecting rod 4; the hydraulic channel 102 is connected to the hydraulic system through a hydraulic pipeline, and is used to pass hydraulic oil; the hydraulic piston 3 is used to drive the connecting rod 4 to move under the action of the hydraulic oil, and drive the blade 2 to rotate through the connecting rod 4.

[0078] The piston-connecting rod mechanism may adopt existing technical products to convert the linear motion of the hydraulic piston 3 into the rotational motion of the blade 2 .

[0079] The hydraulic piston 3 can drive the connecting rod 4 to drive the blade 2 to rotate, expand or retract through telescopic movement to increase or reduce the diameter of the drill bit; so that the blade 2 can be smoothly expanded and retracted during drilling to meet different hole diameter requirements. The drill bit body 1 is used to carry the blade 2 and the driving mechanism, and transmit the torque and axial pressure of the drilling rig. The mud channel 101 is used to ensure the circulation of the drilling fluid and discharge the mud. The hydraulic channel 102 is used to connect the hydraulic pipeline of the hydraulic system and pass the hydraulic oil.

[0080] The hydraulic channel 102 may be provided with a high-pressure hydraulic joint to facilitate connection with the hydraulic system. The diameter of the hydraulic channel 102 may be set to 20-50 mm according to the flow and pressure requirements of the hydraulic system.

[0081] The initial state of the blade 2 can be completely retracted, at which time the blade 2 can be flush with the drill body 1. As the hydraulic piston 2 drives the connecting rod 4 to move and drives the blade 2 to rotate and unfold, the diameter of the drill increases.

[0082] The stroke of the hydraulic piston 3 satisfies the moving distance required for the blade 2 to move from being fully retracted to being fully extended.

[0083] The number of hydraulic channels 102 and hydraulic pistons 3 is equal to the number of blades 2, and the hydraulic channels 102 are connected to the hydraulic pipeline. Each blade 2 corresponds to a hydraulic piston 3, ensuring independent control of the blade 2. The hydraulic pipeline is connected to the hydraulic pump, which can be powered by the drilling rig to generate high-pressure hydraulic oil, and the pressure range is generally 20-35MPa.

[0084] The hydraulic channel 102 is provided with a control valve 5. The control valve 5 can be set as a directional control valve to control the flow direction of the hydraulic oil and realize the forward and backward movement of the hydraulic piston 3. The hydraulic channel 102 can be provided with a pressure regulating valve to maintain the system pressure stable and prevent excessive pressure from damaging the blade 2 or the drive mechanism. The hydraulic channel 102 can be provided with a safety valve to automatically release the pressure when the pressure exceeds the set value to protect the system safety.

[0085] Seals are provided between the hydraulic piston 3 and the control valve 5 and the hydraulic channel 102 to prevent mud and impurities from entering and ensure smooth movement of the hydraulic piston 3 and the control valve 5. The seals can be made of fluororubber or polytetrafluoroethylene (PTFE) seals, such as sealing rings or sealing lips or a combination of the two. In addition, multiple seals can be provided to improve the sealing effect.

[0086] The hydraulic system can be controlled by a drilling rig, and the operator can adjust the hydraulic pressure through the drilling rig on the ground to achieve real-time control of the rotation, deployment or retraction of the blade 2.

[0087] The hydraulic system can be equipped with a filter to remove impurities and protect hydraulic components before the hydraulic oil enters the system; a radiator can be installed to prevent the hydraulic oil from overheating. A temperature sensor can be installed to monitor the hydraulic oil temperature in real time. A pressure sensor can be installed in the hydraulic channel 102 to monitor the pressure changes of the hydraulic system and prevent malfunctions caused by overpressure or underpressure.

[0088] In one embodiment, the driving mechanism is configured as a screw-slider mechanism; the screw-slider mechanism includes a screw, a screw channel and a slider, the screw channel is arranged in the drill body 1, and the screw and the slider are arranged in the screw channel; the slider has an internal threaded hole and is threadedly connected to the screw; the slider is connected to the blade 2.

[0089] Among them, the screw slider mechanism can adopt existing technology products. When the screw is rotated, the slider moves linearly on the screw and simultaneously pushes the blade 2 to rotate, expand or retract, that is, the linear motion of the slider is converted into the rotational motion of the blade 2.

[0090] In one embodiment, the driving mechanism is configured as a cam mechanism; the cam mechanism comprises a cam channel and a cam, the cam channel is disposed in the drill body 1 , the cam is disposed in the cam channel, and the cam contacts the blade 2 .

[0091] The cam mechanism may adopt existing technology products. When the drill bit rotates, the contour curve of the cam pushes the blade 2 to rotate, expand or retract.

[0092] Embodiment 2

[0093] Please refer to Figure 1 and Figure 2 This embodiment provides a method for using the variable drilling diameter drill bit described in Embodiment 1, comprising the following steps:

[0094] Step S1, installing the blade: connecting the top of the drill body 1 to the drilling machine;

[0095] Step S2, retracting the blade: turning on and operating the driving system to drive the blade 2 to rotate and retract, so that the diameter of the drill bit is reduced;

[0096] Step S3, start drilling: the drilling rig provides torque and drilling pressure to drive the drill bit body 1 downward, so that the bottom end of the drill bit body 1 cuts the formation, so that mud flows out of the mud channel 101 and takes out rock cuttings;

[0097] Step S4, increasing the drilling diameter: starting and operating the driving system in reverse, so that the driving blade 2 rotates and expands, thereby increasing the diameter of the drill bit.

[0098] In some embodiments, after step S1 and before step S2, step S11 may be performed, connecting the hydraulic system: connecting the hydraulic channel 102 to the hydraulic system;

[0099] In step S2, the hydraulic system is turned on and operated to drive the hydraulic piston 3 to move, so as to drive the blade 2 to rotate and retract, so that the diameter of the drill bit is reduced, and then the hydraulic system is turned off;

[0100] In step S4, the hydraulic system is turned on and reversely operated to drive the hydraulic piston 3 to move, thereby driving the blade 2 to rotate and expand, so that the diameter of the drill bit increases, and then the hydraulic system is turned off.

[0101] It can be seen that when the diameter of the drill hole needs to be reduced, the blade is retracted in step S2. When the drill bit needs to be lifted, the blade is retracted in step S2 so that the drill bit can pass through the drilled hole smoothly, improving construction safety. When retracting the blade, the hydraulic system can be turned on and operated to drive the hydraulic piston 3 to perform a contraction activity, thereby driving the blade 2 to rotate and retract.

[0102] When increasing the drilling diameter in step S4, the hydraulic system may be turned on and reversely operated to drive the hydraulic piston 3 to extend, thereby driving the blade 2 to rotate and expand.

[0103] In step S3, the initial drilling diameter of the drill bit is the diameter when the blade 2 is fully retracted, which is used for drilling into the starting section or narrow area. The initial drilling diameter may be 1.5 m.

[0104] In step S4, the maximum drilling diameter of the drill bit is achieved by expanding the blades to enlarge the hole diameter, and the maximum drilling diameter can be 2m or 2.5m.

[0105] The maximum drilling depth of the drill bit can be set to 50m. In hard formations, the average drilling speed of the drill bit is ≥1m / h. In loose and soft formations, the average drilling speed of the drill bit is ≥2m / h.

[0106] In step S2, under the action of the drilling rig torque and axial pressure, the drill bit rotates and moves downward, and the blade 2 cuts the soil or rock to form an initial borehole.

[0107] In step S3, when the predetermined depth is reached and the hole diameter needs to be enlarged, the hydraulic system is started, and high-pressure hydraulic oil is provided to the hydraulic piston 3 inside the drill bit through the drilling rig control system; the hydraulic piston 3 moves under the pressure of the high-pressure hydraulic oil and pushes the connecting rod 4, and the connecting rod 4 pushes the blade 2 to rotate outward around the hinge axis 6 to a set angle, thereby increasing the diameter of the drill bit; the drill bit continues to rotate and advance at the enlarged diameter, and the blade 2 cuts the surrounding soil or rock to expand the diameter of the hole.

[0108] In step S2, the hydraulic system pressure is released, or reverse oil supply is performed relative to step S4; under the action of at least one of the weight of the blade 2 and the contraction force of the spring, the blade 2 rotates inward around the hinge shaft 6 and retracts to a position flush with the drill body 1.

[0109] The drilling mud circulates in the mud channel 101 to carry the cuttings to the surface, thereby removing the cuttings and preventing accumulation at the bottom of the hole. At the same time, the mud cools and lubricates the blade 2 and the drill bit, reducing wear and heat accumulation.

[0110] In this system, we can use a torque sensor based on a strain gauge to monitor the drill torque in real time. The sensor is installed at the key part of the drill bit or drill rod, and can directly detect the small strain changes caused by the torque and transmit the data to the control system. Once the torque exceeds the preset value, the system automatically reduces the drilling pressure or stops drilling. This can effectively prevent the drill bit from being damaged due to excessive torque during the drilling process. At the same time, when the hydraulic system fails, the design also sets a mechanism for manually retracting the blade to ensure that the drill bit can be safely withdrawn from the hole.

[0111] In addition, the strength analysis of the variable drilling diameter drill bit described in the first embodiment may include the following contents:

[0112] 1. Load analysis: According to the working environment and stress characteristics of the drill bit, load analysis is performed on key components to determine whether they meet the design requirements.

[0113] 1.1. Normal working load:

[0114] 1.1.1 Axial load (biting pressure):

[0115] (1) Axial load (bit pressure)

[0116] Source: The drilling pressure applied by the drilling rig and the weight of the drill bit.

[0117] calculate:

[0118] Drill bit weight: Calculated based on material density and drill bit size, assuming the total mass of the drill bit is approximately 10 tons (100,000N).

[0119] Drilling pressure: According to the drilling rig capacity, the conventional drilling pressure is 500kN.

[0120] Total axial load:

[0121] F 轴 =F 钻压+ F 自重 =500kn+100kn=600kn

[0122] (2) Torque

[0123] Source: The torque provided by the drill to rotate the drill bit.

[0124] Calculation: Based on the rated torque of the drilling rig, take 50 kN·m.

[0125] (3) Lateral load

[0126] Source: Lateral force caused by factors such as uneven formation and drill bit deviation.

[0127] Calculation: Estimate based on 10% of the axial load, that is:

[0128] F 侧 =0.1×F 轴 =0.1×600kn=60kn

[0129] 1.1.2 Extreme load conditions

[0130] (1) Drilling stuck condition

[0131] Situation: The drill bit encounters an obstacle or an unexpected situation during the drilling process, causing it to get stuck and the load to increase dramatically.

[0132] Calculation: Take 1.5 times the normal working load:

[0133] Axial load:

[0134] F 轴 , 极限 =1.5×F 轴 =1.5×600kn=900kn

[0135] Torque:

[0136] T 极限 =1.5×T=1.5×50kn·m=75kn·m

[0137] (2) Impact load

[0138] Situation: The drill bit encounters hard rock or geological mutation, generating instantaneous impact force.

[0139] Calculation: Take twice the normal lateral load:

[0140] F侧 , 冲击 =2×F 侧 =2×60kn=120kn

[0141] 1.2 Structural strength calculation

[0142] Strength calculations are performed on the blade 2, the hinge shaft 6, and the drill body 1 to ensure that no damage occurs under the maximum load. The hinge shaft 6 can be a pin shaft.

[0143] 1.2.1 Blade strength calculation

[0144] (1) Force analysis

[0145] Cutting force (F 切 ): Produced by the blade cutting the formation, mainly acting on the leading edge of the blade.

[0146] calculate:

[0147] Cutting force formula (according to the Geotechnical Engineering Handbook):

[0148] F 切 =K×A 切

[0149] Among them, K is the unit cutting resistance of rock, which is 20MPa; A 切 Cut is the cutting area.

[0150] Cutting area:

[0151] A 切 =B×t

[0152] Among them, B is the blade width, which is 200mm; t is the cutting depth, which is 10mm.

[0153] Calculation results:

[0154] Fcut = 20 × (0.2 × 0.01) = 40 kn

[0155] (2) Stress calculation

[0156] Bending stress (σ):

[0157]

[0158] Where M = F 切 ×L is the bending moment, L is the lever arm, which is taken as 1m; c is the maximum distance of the section from the neutral axis, and I is the section moment of inertia.

[0159] Section moment of inertia (rectangular section):

[0160]

[0161] Wherein, h is the thickness of the blade 2, which is 50 mm.

[0162] calculate:

[0163] Bending moment:

[0164] M=40kn×1m=40kn·m

[0165] Moment of Inertia:

[0166]

[0167] Maximum stress:

[0168]

[0169] (3) Strength verification

[0170] Material selection: 42CrMo alloy steel is selected. According to GB / T 3077-2015 "Alloy Structural Steel" standard, its yield strength σ s =930MPa.

[0171] Safety factor: take n=2.

[0172] Allowable stress:

[0173]

[0174] Verification result: Since the calculated stress σ=480MPa>[σ]=465MPa, the strength requirement is not met, and it is necessary to increase the thickness of the blade 2 or change the material.

[0175] (4) Optimization measures

[0176] Increase the thickness of blade 2: Increase the thickness of the blade from 50mm to 55mm and recalculate the moment of inertia and stress.

[0177] Use high-strength materials: Consider using 35CrMo alloy steel with a yield strength of σ s =785MPa, but the yield strength is lower than 42CrMo, so it is not recommended.

[0178] Use surface strengthening treatments such as carburizing and quenching to improve surface strength.

[0179] 1.2.2 Pin strength calculation

[0180] (1) Force analysis

[0181] Shear force: The force is transmitted from blade 2 to the pin.

[0182] Bending moment: Due to the length and force position of blade 2, the pin is bent.

[0183] (2) Stress calculation

[0184] Shear stress (τ):

[0185]

[0186] Where A is the cross-sectional area of ​​the pin, assuming the pin diameter is 100 mm:

[0187]

[0188] Bending stress: Due to the short length of the pin, the bending stress can be ignored.

[0189] (3) Strength verification

[0190] Material selection: 45 steel is selected, according to GB / T 6992015 "High-quality carbon structural steel" standard, yield strength σ s =355MPa.

[0191] Allowable shear stress:

[0192]

[0193] Verification results: Since τ=5.1MPa<[τ]=102.5MPa, the pin strength meets the requirements.

[0194] 1.2.3 Calculation of drill bit strength

[0195] (1) Force analysis

[0196] Axial stress: caused by axial load.

[0197] Torsional stress: caused by torque.

[0198] (2) Stress calculation

[0199] Axial stress (σ α ):

[0200]

[0201] Assume that the inner diameter of the drill body 1 is 1.4m, the outer diameter is 1.5m, and the cross-sectional area is:

[0202]

[0203] Torsional stress (τ t ):

[0204]

[0205] Where r is the outer radius and J is the polar moment of inertia:

[0206]

[0207] (3) Strength verification

[0208] Combined stress: According to the third strength theory, calculate the equivalent stress:

[0209]

[0210] Material selection: 42CrMo alloy steel, yield strength σ s =930MPa.

[0211] Safety factor: take n=2.

[0212] Allowable stress:

[0213]

[0214] Verification results: Due to σ 等效 =1411MPa>[σ]=465MPa, which does not meet the strength requirement, and it is necessary to increase the wall thickness of the drill body 1 or change the material.

[0215] (4) Optimization measures

[0216] Increase the wall thickness: Increase the outer diameter of the drill body 1 to 1.6 m, and recalculate the cross-sectional area and torsional moment of inertia.

[0217] Use high-strength material for the drill body 1: consider using ultra-high-strength steel, such as 30CrNiMo8, with a yield strength σ s =1100MPa.

[0218] The above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

[0219] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0220] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to has a specific orientation, is constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0221] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

Claims

1. A variable drilling diameter drill bit, characterized in that: include: The drill bit body (1) is arranged in a columnar shape; A mud channel (101) is provided inside the drill bit body (1); A blade (2) rotatably connected to the drill body (1); A driving mechanism is connected to the blade (2) and is used to drive the blade (2) to rotate, expand or retract, so as to change the diameter of the drill bit.

2. The variable drilling diameter drill bit according to claim 1, characterized in that: The driving mechanism is configured as a piston-connecting rod mechanism; The piston-connecting rod mechanism comprises a hydraulic system, a hydraulic channel (102), a hydraulic piston (3) and a connecting rod (4); the hydraulic channel (102) is arranged in the drill bit body (1); the hydraulic piston (3) is arranged in the hydraulic channel (102) and is connected to the blade (2) via the connecting rod (4); the hydraulic channel (102) is connected to the hydraulic system via a hydraulic pipeline and is used to pass hydraulic oil; the hydraulic piston (3) is used to drive the connecting rod (4) to move under the action of the hydraulic oil, and drive the blade (2) to rotate via the connecting rod (4).

3. The variable drilling diameter drill bit according to claim 1, characterized in that: The driving mechanism is configured as a screw slider mechanism; The screw slider mechanism comprises a screw, a screw channel and a slider, wherein the screw channel is arranged in the drill body (1), and the screw and the slider are arranged in the screw channel; the slider has an internal threaded hole and is threadedly connected to the screw; and the slider is connected to the blade (2).

4. The variable drilling diameter drill bit according to claim 1, characterized in that: The driving mechanism is configured as a cam mechanism; The cam mechanism comprises a cam channel and a cam, wherein the cam channel is arranged in the drill body (1), the cam is arranged in the cam channel, and the cam is in contact with the blade (2).

5. The variable drilling diameter drill bit according to claim 1, characterized in that: The number of blades (2) is at least two, and the plurality of blades (2) are evenly distributed along the circumference.

6. The variable drilling diameter drill bit according to claim 1, characterized in that: The blade (2) is rotatably connected to the drill body (1) via a hinge.

7. The variable drilling diameter drill bit according to claim 6, characterized in that: The hinge comprises a hinge shaft (6) and a hinge seat, the blade (2) and the drill body (1) are respectively provided with the hinge seats, and the two ends of the hinge shaft (6) are respectively connected to the hinge seats.

8. The variable drilling diameter drill bit according to claim 1, characterized in that: The drill bit body (1) is provided with a limiter for limiting the rotational expansion angle of the blade (2).

9. The variable drilling diameter drill bit according to any one of claims 1 to 8, characterized in that: A joint (103) for connecting to a drilling machine is provided on the top of the drill body (1).

10. The method for using a variable drilling diameter drill bit according to any one of claims 1 to 9, characterized in that: The following steps are involved: Installing the blade: connecting the top end of the drill bit body (1) to a drilling machine; Retracting the blade: turning on and operating the drive system to drive the blade (2) to rotate and retract, thereby reducing the diameter of the drill bit; Start drilling: the drilling rig provides torque and drilling pressure to drive the drill bit body (1) downward, so that the bottom end of the drill bit body (1) cuts the formation, and mud flows out of the mud channel (101) and takes out rock cuttings; Increasing the drilling diameter: starting and operating the driving system in reverse, so that it drives the blade (2) to rotate and expand, thereby increasing the diameter of the drill bit.

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